Post-driving device



Dec. 9, 1969 w. MCLEAN MIXON 3,482,639

POST-DRIVING DEVICE Filed April 17, 1 968 3 Sheets-Sheet 1 INVENTOR WILLIAM MCLEAN Ml XON Dec. 9, 1969 w. M LEAN MIXON 3,432,639

POST-DRIVING DEVICE Filed April 17, 1968 3 Sheets-Sheet 2 INVENTOR WILLIAM McLEAN MIXON BY 5M ATTORNEYS Dec. 9, 1969 w. MOLEAN MIXON POST-DRIVING DEVICE 3 Sheets-Sheet 5 Filed April 1.7. 1968 ATTORNEYS United States Patent US. Cl. 173-27 Claims ABSTRACT OF THE DISCLOSURE A post-driving apparatus adapted to be attached to a prime mover, such as a crawler tractor, and to be driven by the power take-off of the tractor, the apparatus comprising a framework for supporting two vertical parallel guide rods which function as guides for a weighted drop hammer and a protective cap fitting over the upper end of a post; the framework being adjustable by three hydraulic means permitting the framework to be tilted in any direction and to be moved short distances in a direction at right angles to the line of movement of the prime mover; the weighted hammer being raised by a winch which is driven by an interrupted driving means receiving its power from the take-off of the prime mover, the interrupted movement being controlled by forcing brake shoes against a brake drum which in turn causes the winch to rotate by the frictional contact between the brake shoes and the brake drum. This apparatus is particularly useful in the driving of posts for fences and similar operations with a drop hammer.

This invention relates to a post-driving apparatus adapted to be mounted on a tractor, and more particularly it relates to a convenient, adjustable apparatus for driving fence posts rapidly, with very little man-power, and with excellent alignment.

Large drop hammer devices have been known for a long time and recently such devices have been mounted on large trucks and heavy track-laying devices to be used in the construction of buildings and in the driving of piles and the like. The setting of fence posts, i.e. wooden posts 4-6" in diameter and 610' long, have not been susceptible to such devices because of the high cost involved in producing such a device and in using it. In recent times, however, certain developments have been made in attempts to produce smaller apparatus which could be attached to a garden tractor or other similar prime mover. These devices have taken either of two forms, (1) all hydraulically operated or (2) friction operated. In the hydraulic form, hydraulic mechanisms have been employed to raise the hammer to an appropriate height and then release it to produce a blow by free fall. Such devices require additional and expensive hydraulic pumping equipment to supply the quantity required for such operations and thereby normally become rather large and heavy machines. The friction driven types are normally those which raise the weight by means of the application of a driven wheel against a vertical, slidable rack in the nature of a rack and pinion gear combination, but such equipment wears very rapidly and normally requires more man-power for its operation than is economical. The present invention provides a drive combination and a structure which essentially eliminate the disadvantages of the prior art and permits a convenient apparatus to be mounted on a small prime mover, such as a crawler tractor.

It is an object of this invention to provide an improved apparatus for driving fence posts or the like.

It is another object of this invention to provide an improved apparatus for driving fence posts, the apparatus being moutned on a small tractor.

3,482,639 Patented Dec. 9, 1969 'ice It is another object of this invention to provide a postdriving apparatus which permits adjustment of the post by hydraulic means to obtain vertical plumb and rapidly driving the post in that condition.

It is still another object of this invention to provide a post-driving apparatus in which substantially all of the driving operations are controlled by the prime mover operator.

It is yet another object of this invention to provide a post-driving apparatus in which the driving mechanism provides an interrupted torque to a winch, the interruption control being provided by forcing brake shoes against a moving brake drum in a hydraulic braking system.

Still other objects will be apparent from the more detailed description of this invention which follows.

This invention may be readily understood by reference to the attached drawings. FIGURE 1 is a side elevational view of the apparatus of this invention. FIGURE 2 is a rear elevational view of the apparatus of this invention. FIGURE 3 is a schematic drawing in elevation of the drive mechanism connecting the power take-01f of the prime mover to be winch which operates the weighted hammer in the apparatus -'of this invention. FIGURE 4 is a cross-sectional view taken along AA of FIGURE 3. FIGURES 5, 6, 7, and 8 are schematic drawings showing the sequence of operations in setting and driving a post with the apparatus of this invention.

Specific reference to FIGURES 1 and 2 will indicate the general features of the apparatus of this invention. Two vertical guide rods 1 are maintained in a vertical, parallel relationship to each other by a framework comprising a series of horizontal channel supports 2, a semi-circular stiffener 3, and a vertical connecting channel 4. This framework not only supports the guide rods 1 in a rigid, parallel relationship, but also supports overhead hanger plate 5 which in turn supports forward pulley 6 and rear pulley 7. Weighted drop hammer 8 is fitted with suitable gibs 9 so that hammer 8 is capable of sliding vertically upward and downward between guide rods 1 without being permitted any substantial movement in a lateral direction. Protective cap 10 is similarly fitted with two pairs of gibs 11 so that it will have the same freedom of vertical sliding movement and restriction of lateral movement as described with respect to hammer 8. Protective cap 10 is formed with a lower recess 12 which is of suitable size and shape to fit over the upper end of a post to be driven into the ground by this apparatus. Protective cap 10 also contains an upper recess 13 into which is placed pillow block 14 which normally is a piece of hard wood, such as oak, for receiving the striking blows of the drop hammer 8. Protective cap 10 is also fitted with suitable eyes and a loose piece of wire rope 15 which when used in conjunction with a suitable hook 16 on hammer 8, serves to tie together hammer 8 and protective cap 10. By means of eye 17, rope 18 is attached to hammer 8 and through pulleys 7 and 6 is attached to winch 19. A spring 20 encircles rope 18 immediately below rear pulley 7 so as to protect the pulley and the upper portion of the framework from the effects of weighted hammer 8 not stopping soon enough in its upward travel.

The entire framework described above which relates to the guide rods, the weighted hammer, and the protective cap, is supported on main support rod 21 and held in place on that rod by attachments to two hydraulic cylinder means. The framework can slide along main support rod 21 from hinge housing 22 to support rod guide 23. The movement of the framework along support rod 21 is controlled by the action of a hydraulic cylinder means comprising cylinder 24, cylinder rod 25, and connector linkage 26. As hydraulic fluid under pressure is supplied to cylinder 24, forcing rod 25 out of the cylinder, the framework moves to the left on support rod 21 and is eventually stopped when it contacts support rod guide 23. Contrarywise, as hydraulic fluid is removed from cylinder 24, rod 25 retracts into the cylinder, moving the framework to the right along support rod 21 until it is stopped by contact with hinge housing 22. A second hydraulic means comprising cylinder 27 and cylinder rod 28 joined to main support rod 21 by connector linkage 29 and joined to support rod guide 23 by connector linkage 30. This hydraulic cylinder assembly serves to move main support rod 21 upward or downward within the limits provided by support rod guide 23. This movement of support rod 21 causes the framework to tilt to the right or to the left about the hinge in housing 22 as a center. The third hydraulic means comprises hydraulic cylinder 31, cylinder rod 32, connector linkage 33, and another connector linkage (not shown) for attaching the closed end of cylinder 31 to the rigid structure which is attached to the prime mover which transports this apparatus. This hydraulic means serves to tilt the upper end of the framework to the rear or to the front as cylinder rod 32 is respectively extended or retracted. Thus, it may be seen that, by means of these three hydraulic assemblies, the entire framework which supports guide rods 1 and drop hammer 8 may be moved in several directions so as to drive the fence post into the ground at the proper location and at the proper angle to the ground. Shadow lines are indicated in FIGURES 1 and 2 to show the various adjusting movements which may be given to the framework by means of the three hydraulic assemblies. The hydraulic assembly comprising cylinder 24 and rod 25 provides lateral movement of the framework between shadow lines 34 and 35. Operation of the hydraulic assembly comprising cylinder 27 and rod 28 provides movement to the framework as indicated by the shadow outline 36 when the framework is tilted to the left and 37 when the framework is tilted to the right. The bydraulic assembly comprising cylinder 31 and rod 32 provides the tilting movement as indicated by shadow lines 38 when the framework is tilted forward and 39 when the framework is tilted to the rear.

The structure which supports main supportrod 21 is whatever may be convenient to fit the configuration of the prime mover to which this apparatus is attached. In the drawings of FIGURE 1 and FIGURE 2, structural steel sections and plate are employed such as that shown at horizontal support 40, tie bar 41, and various angular supports such as that shown at 42. The entire framework is attached to the prime mover at any suitable location and by any convenient means, such as suitable brackets and bolts 43 and 44. Built into this support structure is winch and drive support 45. The drive comprises, in general, a brake drum and brake band 46 and a chain drive 47 which is connected to power take-off 48 of the prime mover, along with suitable levers and control means, such as that shown schematically at 49. For the sake of reference, the general outline in profile of the rear end of a tractor is shown at 50, along with suitable lever controls connected to the various hydraulic assemblies and other mechanisms as shown at 51.

By specific reference to FIGURES 3 and 4, the operation of the drive mechanism and the winch may be understood, since this comprises a principal feature of this invention.

The principal components of this assembly are winch reel 60, brake drum 61, shaft 62, brake band 63, brake shoes 64, drive shaft 65, drive sprocket 66, driven sprocket 67, chain 68, fluid coupling 69, master brake cylinder 70, and brake lever 71.

The general operational functions of these various parts of the drive mechanism are that the power take-off from the prime mover is supplied to shaft '65 which is fitted with sprocket 66 and which drives through chain 68 a driven sprocket 67 which is fixedly mounted on driven shaft 62. The connections between these members are such that so long as the drive shaft is in operation both sprockets and the driven shaft 62 are rotated, since they are directly connected, without the intervention of any clutch mechanism. Winch reel 60 is fixedly attached to one surface of brake drum 61 and these two members are not connected to shaft 62, but are supported concentrically to it by suitable bearings (not shown). Around the outside of brake drum 61 is external brake band 63 which, by suitable control mechanisms that will be described below, can be tightened against brake drum 61. Internally of brake drum 61 is a hydraulic brake shoe assembly adapted to cooperate with the inside surface of brake drum 61. The hydraulic brake shoe assembly comprises brake shoes 64, suitably covered with a brake lining materials connected at one end to hinge linkage 72 and at the other end to slave cylinder 73, all comprising a typical hydraulic brake shoe assembly, such as that employed in vehicles of today. Hydraulic fluid is fed to slave cylinder 73 through hole 75 in shaft 62, and thence through passageway 74 to cylinder 73. Hole 75 communicates through a fluid coupling 69 to master brake cylinder in which a large supply of hydraulic fluid is pressurized by means of a master brake piston 76, the force being applied to piston 76 by means of connecting row 77 and hand lever 71. Fluid coupling 69 is essentially a seal whereby portion 78 rotates With shaft 62 and portion 79 remains stationary.

The entire assembly of brake shoes 64, linkage 72, slave cylinder 73, and passageway 74 is fixed by suitable means with respect to shaft 62, for example, by being mounted on a disk which is atfixed to shaft 62 so that the entire brake shoe assembly rotates with the rotation of shaft 62. When it is desired for winch reel 60 to rotate, hand lever 71 applies force to piston 76 which in turn forces hydraulic fluid under pressure into slave cylinder 73, causing brake shoes 64 to be forced against the interior surface of brake drum 61, causing it to rotate in accordance with the amount of pressure applied and thereby friction developed between brake shoes 64 and brake drum 61. If sufficient force is applied through brake shoes 64, brake drum 61 will rotate at the same speed as shaft 62. If, on the other hand, brake shoes 64 are not provided with sufficient pressure, some slippage will occur and brake drum 61 will rotate, if at all, at a speed slower than the rotational speed of shaft 62.

Referring for a moment back to FIGURES 1 and 2, it may be remembered that winch 19 provides the operational power to lift weighted hammer 8 so that it may apply the force necessary to drive fence posts into the ground. Winch reel 60, in FIGURE 3, is the reel upon which rope 18 of FIGURES 1 and 2 is wound in order to produce a winch operation. It may therefore be seen that the operator, by suitably applying and releasing force to hand lever 71, can cause winch reel 60 to turn, thereby lifting weighted drop hammer 8 to the top of the framework, as shown in FIGURE 1, and then by release of hand lever 71, hammer 8 will drop with a free fall to produce the post-driving force. The operator therefore merely moves hand lever 71 forward and back to raise drop hammer 8 and release it for repeated blows on the post being driven.

Brake band 63 is employed to lock the rotation of brake drum 61 in any suitable position. This is employed for purposes of holding weighted hammer 8 and/or protective cap 10 in any vertical position which is desired. This is also a hand lever operation in which one end of brake band 63 is held by suitable connection to a fixed anchor 80. At the other end of brake band 63, a pin 81 is engaged by a finger 82 of hand lever 83. As lever 83 is moved to the position shown in shadow lines, brake band 63 is tightened over brake drum 71 and may be maintained in that position by any suitable mechanical locking device (not shown), such as a toggle action, a ratchet, or other temporary catch.

In FIGURES 5-8, there is a schematic illustration of the steps involved in driving-a post by means of the apparatus of this invention. The apparatus is shown in FIGURE 5 to be mounted on a tractor 101. The apparatus comprises in its principal features two vertical guide rods 103 with an overhead hanger plate 104 and many supporting members and stiffening members (not shown), all mounted on main support rod 102, with at least three hydraulic assemblies serving to adjust the positioning of the framework comprising guide rods 103 and all of the supporting members holding those rods in a vertical, parallel relationship. Drop hammer 107 and protective cap 108, which are held together by wire rope 109 are supported by rope 106 which leads to the winch assembly (not shown). In the first operation, which is indicated in FIGURE 5, post 105 is set in a generally upright condition with its lower portion in a semi-circular cutout 110 in lower plate 111. Semi-circular cutout 110 is merely a means of locating post 105 generally in the center between guide rods 103. With post 105 in this generally upright condition, hammer 107 and protective cap 109 is lowered slowly and the upper ends of post 105 fitted into a recess in the underneath surface of protective cap 108 designed to fit with ease over the upper end of post 105. When this is done, wire rope connector 109 will automatically disengage itself from the hook on hammer 107 and fall down to the hanging position shown in FIGURE 6.

In FIGURE 6, the operator of the tractor and the post-driving apparatus employs the three hydraulic systems to move the post-driving apparatus in any direction which is necessary in order to place post 105 in the desired position, which normally would be vertically plumb. An operators assistant can help in this regard by applying a spirit level to the fence post and indicate which direction must be adjusted in order to obtain the vertically plumb condition. Shadow lines 112 and 113 indicate how this control might be employed.

In FIGURE 7, with the protective cap 108 being held in place by gravity on the top of post 105, the operator of the apparatus can then proceed to employ the drop hammer by raising hammer 107 to the top of the framework and letting it drop against protective cap 108 in a series of blows until post 105 has been driven into the ground to any desired amount.

In FIGURE 8, one additional adjustment is permitted by the apparatus of this invention; namely, that of adjusting the driven post to a final position to assure that it is vertically plumb as was desired initially. The post may strike the edge of a rock formation underground and thereby be moved slightly off direction by causing the wooden post to bow and when that bowed post is released it would no longer be plumb. The apparatus of this invention, by reason of the hydraulic assemblies which control the movement of the framework, permits the post to be moved in any of the directions that the framework can be moved, thus causing it to be readjusted to its desired, vertically plumb condition. It may be seen in FIGURE 8 that the shadow lines 114 and 115 indicate that the framework of the apparatus can be adjusted in all directions, and so long as protective cap 108 is held over the upper end of post 105, the adjustment will be imparted to post 105. As soon as post 105 has been aligned properly, protective cap 108 is lifted from the top of the post 105 by lowering hammer 107 to the top of protective cap 108, wire rope 109 is attached to the hook on hammer 107, as shown in FIGURE 5, and both hammer 107 and protective cap 108 are lifted away from the top of the post 105 and the tractor moved away to the next post location.

In order to judge the sizing of the apparatus of this invention which might be employed in driving 4-6" diameter wooden posts into ordinary ground, it has been found that the framework holding vertical guides 1 in FIGURES 1 and 2 should measure approximately 12' from its top to the ground level, with the vertical guides 1 being made of 2 /2" O.D. pipe and employing a hammer 8 weighing approximately 600# and a protective cap 10 weighing approximately 75#, the pillow block 14 in protective cap 10 being a piece of hardwood, e.g. oak, approximately 6-8 thick. Hydraulic assemblies are generally 2" diameter cylinders with 8-16" strokes. When this assembly is mounted on a small crawler tractor (e.g. John Deere 1010) being driven with a sprocket at the power take-01f and a sprocket driving the winch with a rotational speed reduction produced by having the diameter of the drive sprocket/diameter of the driven sprocket be approximately /3, the winch is capable of driving approximately 40 strokes per minute with the weighted hammer and requiring only about 6-8 strokes to drive the post 30" into the ground. It is readily apparent that, with the ease of adjustment as desecribed above, this apparatus is capable of a very high productivity in terms of driving a large number of posts per hour in any kind of country.

Among the advantages which may be set forth distinguishing the apparatus of this invention from those of the prior art, are:

(l) A smaller hydraulic system is needed for the present apparatus as compared to prior art systems employing hydraulic equipment to raise the weighted hammer. In the present apparatus, the hydraulic system is employed only for adjusting the framework and, except in very rare instances, only one of the three hydraulic assemblies is used at any one time.

(2) Since this apparatus is mounted on a tractor which is normally 4 /2 wide with a low center of gravity, it has a definite advantage over an apparatus which is mounted on a truck that is 8 wide and does not have such a low center of gravity. This permits the apparatus of this invention to be employed in substantially any type of terrain and in relatively close quarters.

(3) Since the apparatus of this invention employs a mechanism driven from the power take-off for raising the hammer, it is substantially quicker in its operation than the hydraulic systems which require not only a larger hydraulic pumping system and reservoir, but also a substantially greater amount of time to raise the hammer for each stroke.

(4) The apparatus of this invention provides an ease of adjustment and control by reason of the tilting adjustments in two directions and the sliding adjustment in a third direction which not only permits a more rapid adjustment to the post-driving location, but also permits a final adjustment to render the driven post into a vertically plumb position, as shown in FIGURE 8 of the drawings.

(5) The apparatus of this invention is believed to be more economical in both labor costs and engine costs because this apparatus never needs more than two men, one of whom sets the post in the apparatus at the location where it is to be driven into the ground while the other performs all of the operations of driving the prime mover and operating the drop hammer. It can readily be seen that in certain situations, one man could operate the entire system. All controls are located at the tractor operators fingertips and not at the post-driving apparatus, as may be found in some prior art mechanisms. There is no need for an additional motor for a large hydraulic system, since the normal hydraulic system of a small tractor is sufiicient for the present invention.

Although the invention has been desecribed in considerable detail with reference to certain preferred embodiments thereof, it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

What is claimed is:

1. A post-driving apparatus adapted to be attached to a prime mover and to be driven from a power take-oft,

the apparatus comprising a framework maintaining two vertical parallel guide rods in a fixed rigid relationship with each other, a generally horizontal support rod hinged at one end with said framework mounted on the rod in a slidable relationship, a protective cap for receiving the upper end of a post and a weighted hammer for striking said cap, both the cap and the hammer being in vertical sliding relationship with said guide rods and being unable to move in other directions, hydraulic means for sliding said framework along said horizontal support rod, hydraulic means for raising and lowering the unhinged end of said support rod, hydraulic means for tipping said framework radially around said support rod as a center, a winch means for raising and lowering said weighted hammer, said winch being driven in an interrupted manner by the combination of a hydraulic brake shoe assembly rotatably driven by the power take-cit of said prime mover, and a brake drum aflixed to said winch such that by application of hydraulic pressure to said brake shoe assembly the brake shoes expand and drive the brake drum by frictional contact, and means for supplying hydraulic fluid pressure to said brake shoe assembly.

2. The apparatus of claim 1 which includes a means for applying an external brake band to said brake drum for the purpose of holding said weighted hammer in any position along said guide rods.

3. The apparatus of claim 1 which includes means for temporarily attaching said protective cap to said weighted hammer.

4. The apparatus of claim 1 in combination with a crawler tractor.

5. The combination of claim 1 wherein said apparatus is affixed to said tractor by a standard three-point-hitch References Cited UNITED STATES PATENTS 

